The influence of meteorological conditions and coast distance on the abundance and vertical distribution of hyponeuston has been studied in the Gulf of Marseilles at different seasons of the year. The uppermost 0-50 cm superficial layer was sampled with a five-layers (5 x 10 cm) neuston net. Abundance and microstratification of hyponeustonic spp may be disturbed by direct action of the wind. This effect seems to disappear rather quickly as soon as the wind stopped. Nevertheless, an indirect influence of rain and wind can remain for a longer time, until the initial hydrological conditions reappear. Decrease of salinity, increase of turbidity and pollution induce a striking decrease of hyponeustonic spp abundance. Furthermore, the remaining specimens do not exhibit their usual accumulation in the first 10 cm. Therefore, hyponeuston may be used as a rather good indicator of pollution level, at least in some circumstances.